The combined effect of maternal depression and prenatal exposure to PAHs potentiates ill effect of each on children’s neurobehavioral development concludes the study, "Prenatal Exposure to Air Pollution, Maternal Psychological Distress, and Child Behavior" published in Pediatrics. The results of this study could explain rising school related problems among children, which can’t be attributed to their socio-economic status.

Effects of tobacco exposure on brain development

PAHs are air pollutants generated by combustion; fuel exhaust, coal fumes and so on. Their levels are found to be particularly high in sidestream tobacco smoke - 10 fold higher as compared to the mainstream. PAHs along with fine particulate air pollutants cause inﬂammatory effect that injures normal brain development. Moreover, nicotine from tobacco is also believed to alter prefrontal cortex maturation.

Radiological evidence of inflammatory damage caused on yet developing brain has been demonstrated by magnetic resonance imaging (MRI) - seen as areas of increased intensity.

The results of the study, "Prenatal Tobacco Exposure and Brain Morphology: A Prospective Study in Young Children", showed that children who were exposed to secondhand smoke throughout the pregnancy had smaller total brain volumes and smaller cortical gray matter volumes on magnetic resonance imaging (MRI) at 6-8 years of age.